Lynn Barnwell on tue 6 jan 04
I have some industrial type K thermocouples that I received as a =
substitute for the two welded wire type K. These are enclosed in a =
solid metal sheath and are supposidly alot better and last just about =
forever. My question is.... how far do thermocouples have to protrude =
into a kiln interior to register correctly. My original 8 ga type K =
with ceramic insulators stick into the kiln about 2-2 1/2 inches. The =
industrial type only enters about 3/8" due to it's overall length. Will =
it read correctly? and do you need the ceramic sleeve to go over it? =20
My kiln is a 10 cu ft Cone Art BX2827-10.
IT has 3" brick and 1" fiber insulation. IF I have not put everything =
down to make sense out of my question please let me know and I will get =
more facts together.
Looking for answers
Lynn=20
Hinkle Creek Pottery
Corinth, MS
Arnold Howard on tue 6 jan 04
A rule of thumb: a thermocouple should extend into a firing chamber by four
times the width of the thermocouple. It's okay to push it in farther than
that.
Arnold Howard
From: "Lynn Barnwell"
how far do thermocouples have to protrude into a kiln interior to register
correctly. My original 8 ga type K with ceramic insulators stick into the
kiln about 2-2 1/2 inches. The industrial type only enters about 3/8" due
to it's overall length. Will it read correctly? and do you need the ceramic
sleeve to go over it?
Edouard Bastarache Inc. on tue 6 jan 04
Hello Lynn,
if they are the type with the rather "thick" stainless sleeves,
no more than 1 inch inside the kiln.
I used one 3 inches inside at C/9½ and ended up with
a curved one that did not work anymore, so a friend
engineer running 9 90 ton ilmenite reduction furnaces
told the trick.
For S type it is the opposite at high temp, you should
put them 3 inches inside.
Later,
"Ils sont fous ces quebecois"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
iandol on thu 8 jan 04
Dear Lynn Barnwell,=20
The business end of the thermocouple where the Hot Junction is depends =
on the cross section of the wire which is used.=20
This is where electric current is generated by the heat. You only need =
to have the tip inside the kiln to have an idea of what the temperature =
is doing but this only tells you about that point. Some people like to =
use several observation points and have instruments which will give =
multiple readings.
I am not sure that these details are correct (Phil in LV will have the =
good oil) but there is also a Cold Junction in the instrument and this =
allows the pyrometer to be calibrated. Now I am not sure if the cold =
junction reference temperature is 0=BAC or 15=BAC. Does anyone have this =
information, it could be useful to people who want to have a precise =
feeling for the temperature in the kiln.
Best regards,
Ivor Lewis. Redhill, South Australia
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